Threadster privacy policy:

Individual application data is stored on the user device, but is not shared. The following data may be collected, but is not linked to your identity:

Purchases:
    Used for Analytics, and App Functionality

Google Account and Google Drive Integration (Android)

Data Accessed:
When you choose to enable Google Drive backup, Threadster requests the following Google OAuth 2.0 permissions: drive.appdata — Access to a private, app-specific folder in your Google Drive that is not visible to you or other apps. Used to store your Threadster database backup file. drive.file — Access to files created and opened by Threadster in your Google Drive. Used to upload and retrieve your backup files. Threadster does not access your Google account profile, name, email address, contacts, calendar, Gmail, or any other Google service.

Data Usage:
The Google Drive permissions are used solely to: Upload your Threadster thread inventory database to your private Google Drive app folder as a backup. Upload your pattern annotation files to a PatternAnnotations/ folder within your private Google Drive app folder. Download and restore those backup files to your device when you choose to restore. Your backup data is stored in your own Google Drive account. Threadster does not transmit your data to any Threadster servers or third parties.